Latency Reduction in Service Function Paths

1. A computer-implemented method for reducing packet transfer latency in a network overlay, the method comprising: sending a packet along a service function chain (SFC) to an egress node, the SFC comprising a plurality of service function forwarders (SFFs), each of the plurality of SFFs associated with at least one service function (SF); and receiving the packet at a first SFF of the plurality of SFFs, the first SFF associated with a first SF and configured to perform operations comprising: reading an option flag of the packet, determining whether to forward the packet to the first SF based on the option flag, identifying a time delay associated with the packet, determining whether the packet can be delivered to the egress node within a latency threshold based on the time delay, and setting the option flag to indicate that subsequent SF invocation is optional when it is determined that the packet cannot be delivered within the latency threshold or non-optional when it is determined that the packet can be delivered within the latency threshold.

2. The computer-implemented method of claim 1 , wherein determining whether to forward the packet to the first SF based on the option flag further comprises: determining when a function associated with the first SF is a mandatory network function; and forwarding the packet to the first SF when the function associated with the first SF is the mandatory network function.

3. The computer-implemented method of claim 1 , wherein determining whether to forward the packet to the first SF based on the option flag further comprises: determining when a function associated with the first SF is a mandatory network function; and skipping the first SF and forwarding the packet to a second SFF in the SFC the function associated with the first SF is not the mandatory network function and when the option flag indicates that SF forwarding is optional.

4. The computer-implemented method of claim 1 , wherein the option flag comprises information stored in an Internet Protocol (IP) address header of the packet.

5. The computer-implemented method of claim 1 , wherein the option flag comprises information stored between an Internet Protocol (IP) address header and a payload of the packet.

6. A system comprising: at least one processor; a network interface coupled to the at least one processor; and a memory device storing instructions that, when executed by the at least one processor, cause the at least one processor to perform operations comprising: sending a packet along a service function chain (SFC) to an egress node, the SFC comprising a plurality of service function forwarders (SFFs), each of the plurality of SFFs associated with at least one service function (SF); and receiving the packet at a first SFF of the plurality of SFFs in the SFC, the first SFF associated with a first SF and configured to perform operations comprising: reading an option flag of the packet, determining whether to forward the packet to the first SF based on the option flag, identifying a time delay associated with the packet, determining whether the packet can be delivered to the egress node within a latency threshold based on the time delay, and setting the option flag to indicate that subsequent SF invocation is optional when it is determined that the packet cannot be delivered within the latency threshold or non-optional when it is determined that the packet can be delivered within the latency threshold.

7. The system of claim 6 , wherein determining whether to forward the packet to the first SF based on the option flag further comprises: determining when a function associated with the first SF is a mandatory network function; and forwarding the packet to the first SF when the function associated with the first SF is the mandatory network function.

8. The system of claim 6 , wherein determining whether to forward the packet to the first SF based on the option flag further comprises: determining when a function associated with the first SF is a mandatory network function; and skipping the first SF and forwarding the packet to a second SFF in the SFC the function associated with the first SF is not the mandatory network function and when the option flag indicates that SF forwarding is optional.

9. The system of claim 6 , wherein the option flag comprises information stored in an Internet Protocol (IP) address header of the packet.

10. The system of claim 6 , wherein the option flag comprises information stored between an Internet Protocol (IP) address header and a payload of the packet.

11. A non-transitory computer-readable storage medium comprising instructions stored therein, which when executed by one or more processors, cause the processors to perform operations comprising: sending a packet along a service function chain (SFC) to an egress node, the SFC comprising a plurality of service function forwarders (SFFs), each of the plurality of SFFs associated with at least one service function (SF); and receiving the packet at a first SFF of the plurality of SFFs in the SFC, the first SFF associated with a first SF and configured to perform operations comprising: reading an option flag of the packet, determining whether to forward the packet to the first SF based on the option flag, identifying a time delay associated with the packet, determining whether the packet can be delivered to the egress node within a latency threshold based on the time delay, and setting the option flag to indicate that subsequent SF invocation is optional when it is determined that the packet cannot be delivered within the latency threshold or non-optional when it is determined that the packet can be delivered within the latency threshold.

12. The non-transitory computer-readable storage medium of claim 11 , wherein determining whether to forward the packet to the first SF based on the option flag further comprises: determining when a function associated with the first SF is a mandatory network function; and forwarding the packet to the first SF when the function associated with the first SF is the mandatory network function.

13. The non-transitory computer-readable storage medium of claim 11 , wherein determining whether to forward the packet to the first SF based on the option flag further comprises: determining when a function associated with the first SF is a mandatory network function; and skipping the first SF and forwarding the packet to a second SFF in the SFC the function associated with the first SF is not the mandatory network function and when the option flag indicates that SF forwarding is optional.

14. The non-transitory computer-readable storage medium of claim 11 , wherein the option flag comprises information stored in an Internet Protocol (IP) address header of the packet.